1. Field of the Invention
The present invention relates to an optical instrument having a zoom function for varying focal length of an imaging optical system, and being capable of moving a plurality of zoom lens groups independently, and to an imaging device.
2. Description of the Related Art
In order to achieve size reduction of a lens barrel, it has been proposed, instead of a mechanical cam, to drive a front group and rear group of lenses by respective independent motors. For example, Japanese patent laid-open No. Hei. 6-324245 (hereafter referred to as patent publication 1) discloses, in a zoom lens having a front lens group and a rear lens group, a zoom lens unit having a front lens group drive motor and a rear lens group drive motor, that carries out a zoom operation by driving both motors together when a power supply voltage is greater than or equal to a specified value.